The speaker is incorrect. If you can sometimes articulate the sound, it’s NOT an articulation issue. A stutter block is a function of having voluntary fear response (valsalva maneuver) which causes tension in diaphragm and automatically clamps shut of vocal chords. I stopped listening after a series of very incorrect assertions, so it’s possible he accidentally landed on helpful advice. But it’s highly unlikely You don’t have to believe me - but my blocks were so bad, I once went 3 days with broken heat/hot water in the dead of New England winter bc I was so scared to call someone to fix it. When I finally did, and the women on phone realized why I waited so long to call, she felt so bad for me she started to sniffle (cry). By accepting it is an anxiety issue, and by doing the opposite of what I was doing naturally, I’ve had almost complete control of my speech, and even speak more clearly and smoothly than before. It’s been almost a year.